Method for photographing on board of a flying rotating body and system for carrying out said method

ABSTRACT

The invention relates to a method for photographing on board of a flying rotating body and system for carrying out said method. According to said invention, pictures (V 0 , V 90 , V 180 , V 270 ) are taken at predetermined angular positions of said flying body by a device which is rigidly fixed to the front thereof and are exposed to an image geometrical transformation required for the display thereof.

The present invention relates to a method for the formation, on adisplay stationed at a fixed post, of successive images of a scenetowards which a flying body is moving while rotating about itslongitudinal axis. It also relates to a system implementing this method.

Although not exclusively, the invention is particularly appropriate tothe guidance of a rotating attack missile heading for a target and itwill be more especially explained hereinbelow in conjunction with thisapplication.

It is known that such rotating missiles are launched and guided towardstheir target (for example a tank) by means of a firing post, stationedat a fixed post, provided with a picture-taking apparatus and with adisplay. Thus, an operator can observe on said display the successiveimages of the scene in which said target lies, which images areaddressed to said display by said picture-taking apparatus and whichserve the operator in guiding said missile towards the target.

Such a system has the drawback that the missile itself appears on saidimages, so that the flames and/or the smoke emitted by its motorpartially hide said scene, this possibly hampering the accuracy of theguidance of said missile.

To attempt to remedy such a drawback, it would be possible to imagine,by analogy with certain missiles stabilized in roll over theirtrajectory, mounting a camera aboard said rotating missile. However, itwould then be indispensable to provide a roll-stabilized platform toreceive said camera. However, the cost of a stabilized platform such asthis is significant and it would not accord with common sense to use oneon board a missile whose destruction is inevitable on first use.

The object of the present invention is to remedy these drawbacks.

To this end, according to the invention, the method for the formation,on a display stationed at a fixed post, of successive images of a scenetowards which a flying body is moving while rotating about itslongitudinal axis, said flying body communicating with said fixed postby virtue of linking means, is noteworthy in that

-   -   a picture-taking apparatus is fixed rigidly to the front of said        flying body, in such a way that said picture-taking apparatus        turns with said flying body about said longitudinal axis;    -   during each revolution of the rotation of said flying body about        said longitudinal axis, several pictures of said scene each        corresponding to a predetermined angular position of said flying        body about said longitudinal axis are taken with said apparatus,        so that the contours of said pictures are inclined in mutually        differing manners and that, in each picture, the image of said        scene and said contour occupy a relative position which depends        on said corresponding predetermined angular position of said        flying body and which is different from that of the other        pictures;    -   among said pictures, a reference picture is determined in which        said relative position between the image of the scene and the        contour is considered to be a relative reference position;    -   in each picture, other than the reference picture, a geometrical        image transformation processing is applied to the image of said        scene so that the relative position of the transformed image of        said scene with respect to the contour is similar to said        relative reference position; and    -   said reference picture and said pictures having undergone said        geometrical image transformation processing are displayed        successively on said display.

Thus, the image of said flying body may not lie on said pictures and itis not necessary to provide a stabilized platform on said rotatingflying body.

A system implementing the method of the invention and comprising:

-   -   at least one flying body, rotating about its longitudinal axis        as it flies;    -   a fixed post furnished with a display able to display successive        images of a scene towards which said flying body is moving while        rotating; and    -   linking means allowing the communications between said flying        body and said fixed post,        is noteworthy in that it furthermore comprises:    -   a picture-taking apparatus, fixed rigidly to the front of said        flying body so as to observe said scene;    -   means for the control of said picture-taking apparatus at each        of several predetermined angular positions of said flying body        about said longitudinal axis; and    -   means of geometrical image transformation processing making it        possible to present the pictures taken by said apparatus at        different angular positions with a similar relative position of        the image of said scene with respect to the contour of said        pictures.

Preferably, said means of control of the picture-taking apparatusconsist of a gyroscopic system mounted on board said flying body andsensitive to the rotation of the latter contour of its longitudinalaxis.

On the other hand, for obvious reasons of payload aboard the flyingbody, it is advantageous that said image processing means be stationedat the fixed post. In this case, the link between said picture-takingapparatus and said image processing means may be effected by said meansof linking between said flying body and said fixed post.

Additionally, it is advantageous that the operation of said imageprocessing means be controlled by said gyroscopic system by way of saidmeans of linking between said flying body and said fixed post.

In case of insufficient lighting of said scene for taking ofsatisfactory pictures of said scene, the system in accordance with thepresent invention can comprise means of illumination, mounted on boardsaid flying body and able to light said scene. The operation of saidmeans of illumination can be synchronized with that of saidpicture-taking apparatus. Preferably, said means of illumination areintegrated into the latter.

The figures of the appended drawing will elucidate the manner in whichthe invention may be embodied. In these figures, identical referencesdesignate similar elements.

FIG. 1 illustrates, diagrammatically, a system applying the method inaccordance with the present invention.

FIG. 2 is the schematic diagram of said system.

FIG. 3 illustrates, diagrammatically, the manner of operation of thesystem of FIGS. 1 and 2.

Represented diagrammatically in FIG. 1 is an attack missile M flyingtowards a target T forming part, together with other elements E (onlyone of which is represented) of a scene S. Moreover, the missile Mrotates about its longitudinal axis. L-L as is illustrated by thecircular arrow F of FIGS. 1 to 3.

The missile M is launched and guided from a firing post PT served by atleast one operator (not represented) The missile M and the firing postPT are connected together by a link 1 allowing exchange of information.Such a link 1 may be embodied by RF waves or by a cable, electrical oroptical, unfurling from said missile M.

The missile M carries, in its nose tip a camera 2, for example anelectronic camera of CCD or CMOS type, observing the scene S from whichit receives light rays R. Possibly, said missile M comprises anilluminator—possibly incorporated with the camera 2—lighting said sceneS, to which it addresses light rays I.

Additionally, the firing post comprises a display 3, on which appear theimages of the scene S, taken by the camera 2 and transmitted to saiddisplay 3 via the link 1.

In customary fashion, in the missile M is moreover provided a gyroscopicsystem 4, necessary for the deviometry measurements relating to saidmissile. By construction, the gyroscopic system 4 is able to deliver theinstantaneous value θ of the angle of rotation of the missile M withrespect to the vertical Z-Z (FIG. 3).

The camera 2 is controlled by the gyroscopic system 4 in such a waythat, at each revolution of said missile about its longitudinal axisL-L, said camera takes an image V₀, V₉₀, V₁₈₀ and V₂₇₀ of the scene Swhen the angle θ takes each of the values 0°, 90°, 180° and 270° (seeFIG. 3).

Thus, if the rate of rotation of the missile M lies between 5 and 10revolutions per second, the camera 2 takes from 20 to 40 images persecond.

To avoid the blurring of the images, the latter are acquired in a veryshort time, in a mode known as “snap shot”, according to which asimultaneous acquisition is carried out of the images on all the pixelsof the sensitive matrix of the camera 2, during a short integrationtime.

Additionally, the firing post PT comprises an image acquisition device5, receiving the images—in electronic form—taken by the camera 2 andtransmitted via the link 1. It furthermore comprises a geometrical imagetransformation device 6, interposed between the acquisition device 5 andthe display 3. The geometrical image transformation device, generallydesignated by the title WARPER, may comprise, inter alia, the TMC 2301component, manufactured by the American company TRW LSI and designatedby the name Image Resampling Sequencer.

Just like the camera 2, the geometrical image transformation device 6 issequenced by sequencing signals originating from the gyroscopic system 4and conveyed by the link 1, as symbolized by the link 7.

Thus, as illustrated by FIG. 3, in the course of a revolution of themissile M about its longitudinal axis L-L, the camera 2 takes:

-   -   a reference picture V₀ on which appears the image s (represented        solely by the silhouette of the target T in FIG. 3) of the scene        S, corresponding to θ=0°, whose contour C exhibits a lower edge        B and an upper edge H;    -   a picture V₉₀, corresponding to θ=90°, whose orientation has        turned by 90° with respect to the reference picture V₀, so that        now the left and right lateral edges of the contour C of said        picture V₉₀ correspond respectively to the lower B and upper H        edges of the contour C of the reference picture V₀;    -   a picture V₁₈₀, corresponding to θ=180°, whose orientation has        turned by 180° with respect to the reference picture V₀, so that        now the upper and lower edges of the contour C of said picture        V₁₈₀ correspond respectively to the lower B and upper H edges of        the contour C of the reference picture V₀; and    -   a picture V₂₇₀, corresponding to θ=270°, whose orientation has        turned by 270° with respect to the reference picture V₀, so.        that now the left and right lateral edges of the contour C of        said picture V₂₇₀ correspond respectively to the upper H and        lower B edges of the contour C of the reference picture V₀.

To ensure that, on the display 3, the relative position of the image sof the scene S and of the contour C is the same in said pictures V₀,V₉₀, V₁₈₀ and V₂₇₀, the geometrical image transformation device 6transforms:

-   -   through a transformation t1, the picture V₉₀ into a picture V′₉₀        in which the image s of the scene S is turned by 90°, so that        the lower and upper edges of the frame C of this picture V′₉₀        correspond respectively to the lower B and upper H edges of the        reference picture V₀;    -   through a transformation t2, the picture V₁₈₀ into a picture        V′₁₈₀ in which the image s of the scene S is turned by 180°, so        that the lower and upper edges of the frame C of this picture        V′₁₈₀ correspond respectively to the lower B and upper H edges        of the reference picture V₀; and    -   through a transformation t3, the picture V₂₇₀ into a picture        V′₂₇₀ in which the image s of the scene S is turned by 270°, so        that the lower and upper edges of the frame C of this picture        V′₂₇₀ correspond respectively to the lower B and upper H edges        of the reference picture V₀.

Thus, the pictures V₀, V′₉₀, V′₁₈₀ and V′₂₇₀ can appear successively onthe display 3, giving the operator the impression of the continuity ofthe images of the scene S.

Possibly, in the unfavorable case of very weak lighting of the scene S,the illumination means incorporated into the picture-taking apparatus 2are operated so as to light the scene S (light rays R) and to increasethe lighting thereof in synchronism with the taking of pictures of saidapparatus 2. These illumination means advantageously comprise a laserdiode or a Vcsel laser as illumination component.

1-7. (canceled)
 8. A method for the formation, on a display (3)stationed at a fixed post (PT), of successive images (s) of a scene (S)towards which a flying body (M) is moving while rotating about itslongitudinal axis (L-L), said flying body (M) communicating with saidfixed post (PT) by virtue of linking means (1), characterized in that apicture-taking apparatus (2) is fixed rigidly to the front of saidflying body (M), in such a way that said apparatus (2) turns with saidflying body (M) about said longitudinal axis (L-L); during eachrevolution of the rotation of said flying body (M) about saidlongitudinal axis (L-L), several pictures of said scene (S) eachcorresponding to a predetermined angular position of said flying bodyabout said longitudinal axis are taken with said apparatus (2), so thatthe contours (C) of said pictures are inclined in mutually differingmanners and that, in each picture, the image (s) of said scene (S) andsaid contour (C) occupy a relative position which depends on saidcorresponding predetermined angular position of said flying body (M) andwhich is different from that of the other pictures; among said pictures,a reference picture (Vo) is determined in which said relative positionbetween the image (s) of the scene (S) and the contour (C) is consideredto be a relative reference position; in each picture, other than thereference picture, a geometrical image transformation processing isapplied to the image (s) of said scene (S) so that the relative positionof the transformed image of said scene with respect to the contour issimilar to said relative reference position; and said reference pictureand said pictures having undergone said geometrical image transformationprocessing are displayed successively on said display (3).
 9. A systemcomprising: at least one flying body (M), rotating about itslongitudinal axis (L-L) as it flies; a fixed post (PT) furnished with adisplay (3) able to display images of a scene (S) towards which saidflying body (M) is moving while rotating; and linking means (1) allowingthe communications between said flying body (M) and said fixed post(PT); a picture-taking apparatus (2), fixed rigidly to the front of saidflying body (M) so as to observe said scene (S); means (4) for thecontrol of said picture-taking apparatus (2) at each of severalpredetermined angular positions of said flying body (M) about saidlongitudinal axis (L-L); and means (6) of geometrical imagetransformation processing making it possible to present the picturestaken by said apparatus (2) at different angular positions with asimilar relative position of the image (s) of said scene (S) withrespect to the contour (C) of said pictures.
 10. The system as claimedin claim 9, characterized in that said means (4) of control of thepicture-taking apparatus (2) consist of a gyroscopic system mounted onboard said flying body (M) and sensitive to the rotation of the lattercontour of its longitudinal axis (L-L).
 11. The system as claimed inclaim 9, characterized in that said image processing means (6) arestationed at the fixed post (PT).
 12. The system as claimed in claim 11,characterized in that the link between said picture-taking apparatus (2)and said image processing means (6) is effected by said means of linking(1) between said flying body (M) and said fixed post (PT).
 13. Thesystem as claimed in claim 10, characterized in that the sequencing ofthe operation of said image processing means (6) is controlled by saidgyroscopic system (4) by way of said means of linking (1) between saidflying body (M) and said fixed post (PT).
 14. The system as claimed inclaim 9, characterized in that it comprises means of illumination (2),mounted on board said flying body (M) and able to light said scene (S).